2. Definition
Waste-to-energy is the process of generating energy in the form
of electricity or heat from the primary treatment of waste.
WtE is a form of energy recovery.
MostWtE processes produce electricity and/or heat directly through
combustion, or produce a combustible fuel commodity, such
as methane, methanol, ethanol or synthetic fuels
3. Incineration
Incineration is the process of combustion of waste for energy recovery.
Modern incinerators reduce the volume of the original waste by 95-96 percent,
depending upon composition and degree of recovery of materials such as metals
from the ash for recycling.
Incinerators have electric efficiencies of 14-28%.
4. Gasification
Gasification is a process that converts organic or fossil
fuel based carbonaceous materials into carbon monoxide, hydrogen and carbon
dioxide.
The material is reacted at high temperatures (>700 °C), without combustion,
with a controlled amount of oxygen and/or steam.
5. Thermal Depolymerization
Thermal depolymerization (TDP) is a depolymerization process
using hydrous pyrolysis for the reduction of complex organic
materials (usually waste products of various sorts, often biomass and plastic)
into light crude oil.
Under pressure and heat, long chain polymers of hydrogen, oxygen,
and carbon decompose into short-chain petroleum hydrocarbons with a
maximum length of around 18 carbons.
6. Pyrolysis
Pyrolysis is the process of thermochemical decomposition of organic material at
elevated temperatures in the absence of oxygen
The process is used to convert plastic and tire waste into fuel.
7. Plasma Gasification
Plasma gasification is an extreme thermal process using plasma which
converts organic matter into a syngas (synthesis gas) which is primarily made up
of hydrogen and carbon monoxide.
A plasma torch powered by an electric arc, is used to ionize gas
and catalyze organic matter into syngas with slag remaining as a byproduct.
It is used commercially as a form of waste treatment and can be highly useful in
treating hazardous waste.
8. Anaerobic digestion
Anaerobic digestion is a collection of processes by
which microorganisms break down biodegradable material in the absence
of oxygen.The process is used for industrial or domestic purposes to manage
waste or to produce fuels.
Anaerobic digestion is particularly suited to organic material, and is commonly
used for industrial effluent, wastewater and sewage sludge treatment.
9. Fermentation
Fermentation is the primary means of producing energy by the degradation of
organic nutrients anaerobically.
Hydrogen production by fermentative bacteria is technically simpler than by
photosynthetic bacteria.Also, the fermentation process generates hydrogen
from carbohydrates obtained as refuse or waste products.
10. Mechanical Biological Treatment
A mechanical biological treatment (MBT) system is a type of waste
processing facility that combines a sorting facility with a form of biological
treatment such as composting or anaerobic digestion. MBT plants are designed
to process mixed household waste as well as commercial and industrial wastes.
The‘mechanical’ element is usually an automated mechanical sorting stage.This
either removes recyclable elements from a mixed waste stream (such as metals,
plastics, glass and paper) or processes them.
